In some cases the virus can cause severe illness and even death. Eight of the state’s nine reported cases last year were in Clark County.

The Carson City environmental health specialists and mosquito abatement staff routinely survey known breeding sources for mosquitoes and trap them for identification.

In addition to West Nile virus, mosquitoes are tested for Western equine encephalitis and St. Louis encephalitis.

Officials recommend the following to prevent mosquito bites and eliminate breeding sources:

■ Apply an insect repellent containing DEET, and follow the manufacturer’s directions. Repellents containing picaridin and oil of lemon eucalyptus also have some efficacy. However, DEET is the best-studied and most-effective repellent available.

■ Wear pants and long-sleeved shirts when outdoors.

■ Avoid spending time outside when mosquitoes are most active, notably at dusk (the first two hours after sunset) and dawn.